I often receive emails about bumble bee nests in compost bins. At this time of year (May, as I write), one common query concerns the desire to move a bumble bee nest out of a compost bin, due to a garden design overhaul, and intention to relocate the compost bin or get rid of the bin completely.
I had such a query this past weekend. Here is a summary of the query:
Above: Some film of a bumble bee (Bombus hypnorum)
nest in our compost bin a few years ago.
I am aware that some websites give advice on carrying out this task. However, I never recommend attempting to move a bumble bee nest located in a compost bin.
Damaging the nest is highly likely in this scenario, ultimately leaving the bumble bees vulnerable. With careful consideration, most people are quite happy to delay moving the compost bin for a little while, in order to help the bees - the nest is only temporary after all.
The difficult question to answer is when the colony will be over - providing a time frame is tricky, but colonies will usually be over in a few weeks.
Here was my reply to the most recent query.
Thanks for your email - and for caring about the bees.
I was in a similar position a few years ago. We decided to get rid of the compost bin completely, because of limited space and the decision to grow flowers in that particular spot instead. However, we had a 'tree bumble bee' nest (Bombus hypnorum) in the compost heap, so we waited.
Regarding the nest in your own compost bin, at some point, the colony will die naturally on its own after males and new queen bumble bees have emerged. For a little while, you'll notice more activity around the nest, followed by notably less, and then no activity. At that point, you can safely move the compost heap. In case a new queen has chosen the compost bin for a snooze, you could be a little cautious and wear gloves and long sleeves although a sting would be an accident.
I can't say exactly what the timescale will be, as it depends on the current stage of the colony life cycle, but in any event, it should all be over by early autumn, and probably much sooner. I should perhaps mention that if they are Bombus hypnorum, at some point you'll see a 'drone cloud' near the entrance of the nest. These are males waiting for the young queens to emerge. The drone cloud may look threatening but the males cannot sting - they are simply interested in the new queens. If one flies close to you, it may be investigating, but males cannot sting at all. If you see a drone cloud, the colony will soon be over. You'll only see the drone cloud if its this particular species (Bombus hypnorum).
I can't really advise on attempting to move the compost bin with the nest. This would be very tricky indeed and damage is likely to occur. Ordinarily, a nest should only be moved at night time, because attempting it during the day would be more likely to provoke angry bees, and there may be some orientation confusion for bees attempting to return to the nest. Also, moving nests is really only the last resort. It would be best if you can wait a little while, then move it once the nest is finished with.
I hope this helps,